Proceeding International Conference, 2013, *, **-** The 4th Green Technology Faculty of Science and Technology Islamic of University State Maulana Malik Ibrahim Malang
ELECTRICAL PROPERTIES OF CaCO3 FILLED CHITOSAN-PVA MEMBRANES Khotimatul munawaroh1, Erna Hastuti2 1,2
Department of physics, Faculty of Science and Technology, Maulana Malik Ibrahim State Islamic University (UIN) of Malang, Indonesia 1 Email:
[email protected] 2
[email protected]
ABSTRACT Membrane techonolgy is used in various applications, one of them is for fuel cell. The electrical properties of CaCO3 filled chitosan-PVA membranes (conductivity, permittivity and impedance) have been analized. The membrane used in this study were syntesized via chitosan and PVA which is filled with various CaCO3 consentration : 0, 0.1 0.2 0.3 and 0.4 gr. The purpose of CaCO3 filling is for increasing capacity of membrane in releasing proton. CaCO3 has ionic bonding with negative charged compounds. From experiment result, it is obtained impedance (Z) and permittivity (ε) values from which showed dielectrical material inside membrane. It also has two kind polarization orientations that are space charge and dipolar. Proton conductivity was increased around 1.32 x 10-4 S/cm-1 when 0.4 g CaCO3 consentration was added Keywords Alternative energy, Proton exchange membrane, fuel cell, CaCO3, Chitosan, Polyvinyl alcohol
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Proceeding International Conference, 2013, *, **-** The 4th Green Technology Faculty of Science and Technology Islamic of University State Maulana Malik Ibrahim Malang
INTRODUCTION Fuel Cell discovered more than 150 years ago by Schoenbein and William Robert Grove (1839). William, an inventor and physicis, was a trial judge which born on 11 July 1811 in Swansea, South Wales and died in London on August 1896 (Muliawati, 2008). Membrane is a thin layer that serves as a solid electrolyte. An anode and a cathode separator selectively control the transport of protons in a fuel cell. PEMFC contains a platinum catalyst to produce energy, which requires only hydrogen, oxygen from the air and also water in operation. In addition, fuel cell does not use corrosive fluid (Jamal R et al., 2007). Development of technology membrane has a various applications, especially on the development in the field of energy. This study was conducted an alternating of the existing membrane is Nafion® Therefore, many new materials are developed and are expected to replace the function of Nafion®. Polymer Electrolyte Membrane (PEM) Fuel Cell can be directly converted from chemical energy to electrical energy through electrochemical process. The functions of membrane are as an electrolyte and a separator between transport gas reactants and hydrogen ions from the anode to the cathode which generated electrical energy. Chitosan is a linear polymer with a high molecular weight of 2-deoxy-2-amino glucose. It has the chemical name that is (1-4)-2-aminodeoxy-β-D-glucose (Rha, 1984). It is also one of derivative chitin whic is obtained by deacetylation or omission COCH3 group (Purwatiningsih, 1993).It also includes a natural polysacharide comprising copolymers of glucosamine. N-acetylglucosamine is derived from industrial processed exoskeleton of crustaceans. (Illum, 1998). Chitosan is non-toxic, biodegradable and cationic polyelectrolyte due to functional group causing a positively charged (Ornum, 1
1992), in addition to the amino group, there are also primary and secondary hydroxyl groups. The presence of functional groups in chitosan has a high chemical reactivity. Which allows chemical modifications including a diverse reactions with crosslinking agent, chitosan can be used as ingredients bioplastics, ie plastics that can be degraded and does not pollute the environment (Putu, 2007). Polyvinyl alcohol is a substance that is not tasteless, odorless and biocompatible. It also can be broken down by nature and dissolved in water. Polyvinyl alcohol is also soluble in ethanol. However, these substances do not dissolve in organic solvents. Electrolyte membranes with PVA mixture exhibit mechanical properties and thermal. The polymer membrane has good strength and easily modified. PEM is suitable for alkaline batteries and other electrochemical systems. Type of alkaline solid polymer electrolyte membranes modified by using PVA was able to produce a high ion conductivity (Dewi, 2011). Calcium carbonate can be formed through chemical reactions, and its constituent elements is none other than calcium (Ca), carbon (C) and oxygen (O). It has the hexagonal-shaped structure (Junaidi, 2010). Physical properties of CaCO3 1. Molecular weight :100.09 g/mol 2. Density :2.8 gr/cm3 3. Melting point :825°C 4. Shaped crystals or powder. 5. Colorless or white. 6. Odorless and tasteless. This study aims to determine the electrical properties of the membrane fuel cell made of chitosan-PVA with the addition of various CaCO3 concentration. Measurement of electrical properties includes proton conductivity, impedance and permittivity.
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A. Name (of the first author) et al. * (2013) **-**
Materials and Methods
Imginary permitivtty: Where D is dissipation factor,
The research was conducted by extracting chitosan from crab shells. Chitosan extraction was processed in that are deproteination, demineralization and deacetylation.(Aryanto, 2002). 7 g of chitosan was dissolved in 2% acetic acid 1:10 w/v, and stirred for 6 hours. Polyvinyl alcohol was dissolved in hot water with a ratio of 1:10 w/v and stirred until homogeneous. Chitosan-acetic acid added into PVA solution 1:4 wt% and stirred until homogeneous. 2.3 g of chitosan-PVA was dissolved in 40 ml of 10% acetic acid solution. It is also added with CaCO3 with ratio 0, 0.1, 0.2, 0.3 and 0.4 g of chitosan-PVA. The suspension was heated at 70°C and stirred with a speed for 600 rpm. Mixture is poured into molds which has 10 cm in diameter and stored at room temperature for 24 hours, then it was dried at a temperature of 60°C for 2 days. Formation of crosslinking was performed by immersing membrane in 0.8 ml Glutaraldehyde (C5H8O2) solution 3%, which were mixed with 30 ml of 6% H2SO4 for 2 days. Finally, the membrane was washed by using distilled water and dried it at room temperature for 24 hours (Rermux et al., 2010).
......... (2) ….… (3)
R e a lP e rm itiv ity
From experiment data were obtained relationship between permitivity and frequency 0 gr 0,1 gr 0,2 gr 0,3 gr 0,4 gr
300 250 200 150 100 50 0 0
1000 Frequency (Hz)
2000
Fig 1. Relationship with the frequency of the variation of the real permittivity addition CaCCO3
0 gr 0.1 gr 0.2 gr 0.3 gr 0.4 gr
Im a g in a ryP e rm itiv ity
1000
Results
800 600 400 200 0 0
Characterization of Electrical Properties of Membranes
1000 Frequency (Hz)
2000
Fig 2. Relationship with the frequency of the variation of the imaginary permittivity addition CaCCO3
This experiment performed using the electrical properties of LCR Meter 816. The applied voltage is 1 volt.
Impedance
Permittivity
Measurements real and imaginary impedance are given by the bellow equation:
Measurements real and imaginary permittivity are given by the bellow equation (Hastuti, 2004)
Real Impedance
Real permitivity:
..............
......... (1) Imaginary Impedance 3
(4)
A. Name (of the first author) et al. * (2013) **-**
..........
4
(5)
R e a lI m p e d a n c ex 1 0
3
By entering data, is obtained graphs 3 and 4. 0 gr 0.1 gr 0.2 gr 0.3 gr 0.4 gr
200 150 100 50
Fig 5. Relationship with the proton conductivity of CaCO3 concentration on the frequency variation
0 0
500
1000
1500
2000
Discussion
Fig 3. Relationship between frequency Frequency (Hz)and impedance real of the variation concentration of CaCO3
The formation of peaks on the fig. 1 and 2 shows the polarization of the membrane. Polarization of the space charge polarization (Space Charge) occurred at a frequency of 100 and 500 Hz and dipolar polarization occured at a frequency of 1000 Hz. Permittivity is influenced by the amount of charge in sample. The more the charge in the material, the higher the chances of polarization. The increasing is caused capacitance caused by the weakening electric field between two capacitor plates. Fig. 3 and 4 show the relation between frequency and impedance. Impedance is influenced by resistance, reactance and frequency. The average value decreases with increasing frequency. This suggests that at low frequencies capacitive reactance (Xc) is greater than inductive reactance (XL). Impedance values is inversely related to frequency, so it has small resistivity and large capacity. This means that the material has good conductivity. Proton conductivity is showed by fig. 5. This parameter is also affected by acid strength, chemical structure, membrane morphology and temperature. The events of proton transfer are caused by leaping hydroxide ions from amine protonation group to another group. This event is known as Grotthus (jump mechanism) (Wilkinson et al., 2010). From the data was obtained by the addition of CaCO3 variations af-
Fig 4. Relationship between frequency and impedance imaginary of the variation of concentration of CaCO3
Proton conductivity Measurements of proton conductivity using equation (Liong, 2009): ....................
(6)
Where σ = conductivity L = thickness of the membrane A = area of membrane R = resistance
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A. Name (of the first author) et al. * (2013) **-**
fecting proton conductivity value. CaCO3 has a high molecular weight and bringing the particles dispersed. It has function as anions in the membrane and interacts with the proton.
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Junaidi. 2010. Karakterisasi Resistansi dan Kapasitansi Cangkang Kerang Menggunakan Metode RLC. Malang: Skripsi, Fakultas Saintek UIN Maliki Malang Liong, A. 2009. Chitosan-Poly (Vinyl Alcohol) and Calcium Oxide Composite Membrane for Direct Methanol Fuel Cell Applications. Malaysia: Engineering Letters
Conclusion The characterization of the electrical properties of the membrane showed that impedance values is reduced with increasing frequency. The smallest impedance value at frequency 2 KHz with a concentration of 0.4 g CaCO3. Permittivity of membrane showed a polarization space charge and dipolar polarization as the peak formed at a frequency of 100 Hz to 1000 Hz. It showed that membrane including a dielectric materials. Proton conductivity is increase with an addition of various CaCO3 concentration. The maximum conductivity is 1.32 x 10-4 S/cm-1 at concentration of 0.4 g CaCO3.
Muliawati, Neni. 2008. Hidrogen Sebagai Sel Bahan bakar: Sumber Energi Masa Depan. Lampung: JurusanTeknik Kimia Universitas lampung Ornum, J. V. 1992. Shrimp Waste Must It be Waste?. Infofish 27 Februari 2013 Purwatiningsih. 1993. Isolasi Khitin dan Senyawa Kimia dari Limbah Udang Windu (Penaus Monodon). Bogor: Buletin Kimia no.8. Jurusan Kimia Fmipa-IPB Putu, Agung W. 2007. Pembuatan Kitosan dari Kulit UdangWindu. Lampung: Universitas Lampung Rermux, N. and Panu D. 2010. Ionic Conductivity of Carbon Black-Filled ChitosanGrafted-Poly (vinyl Alcohol)/Poly (Vinyl Alcohol) Membranes. Thailand. Jurnal Penelitian pdf Rha, C. K. 1984. Chitosan as a Biomaterial. Dalam R. R Colwell, dkk. Biotechnology in the Marine Science. New York: John Wiley and Sons Wilkinson, D et al. 2010. Proton Exchange Membrane Fuel Cell Material Properties and Performance. USA: CRC Press
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